Evaluation of methods for MR imaging of human right ventricular heart volumes and mass.

PURPOSE: To assess the utility of two different imaging directions in the evaluation of human right ventricular (RV) heart volumes and mass with MR imaging; to compare breath-hold vs. non-breath-hold imaging in volume analysis; and to compare turbo inversion recovery imaging (TIR) with gradient echo imaging in RV mass measurement. MATERIAL AND METHODS: We examined 12 healthy volunteers (age 27-59 years). Breath-hold gradient echo MR imaging was performed in two imaging planes: 1) perpendicular to the RV inflow tract (RVIT view), and 2) in the transaxial view (TA view). The imaging was repeated in the TA view while the subjects were breathing freely. To analyze RV mass using TIR images, the RV was again imaged at end-diastole using the two views. The RV end-diastolic cavity (RVEDV) and muscle volume as well as end-systolic cavity volume (RVESV) were determined with the method of discs. All measurements were done blindly twice to assess repeatability of image analysis. To assess reproducibility of the measurements, 6 of the subjects were imaged twice at an interval of 5-9 weeks. RESULTS: RVEDV averaged 133.2 ml, RVESV 61.5 ml and the RVmass 46.2 g in the RVIT view and 119.9 ml, 56.9 ml and 38.3 g in the TA view, respectively. The volumes obtained with breath-holding were slightly but not significantly smaller than the volumes obtained during normal breathing. There were no marked differences in the RV muscle mass obtained with gradient echo imaging compared to TIR imaging in either views. Repeatability of volume analysis was better in TA than RVIT view: the mean differences were 0.7 +/- 4.0 ml and - 5.4 +/- 14.0 ml in end-diastole and 1.6 +/- 3.1 ml and - 1.5 +/- 13.9 ml in end-systole, respectively. Repeatability of mass analysis was good in both TIR and cine images in the RVIT view but slightly better in TIR images: - 0.5 +/ -2.4 g compared to 0.8 +/- 2.9 g in cine images. Reproducibility of imaging was good, mean differences for RVEDV and RVESV were -1.0 +/- 4.8 ml and -0.8 +/- 2.8 ml, respectively. Mean difference for RVmass was -0.9 +/- 2.6 g. CONCLUSION: The present study suggests that gradient echo MR imaging is well applicable to RV volume and mass measurements. The best imaging plane for volumetric analysis seems to be the TA plane and there was no significant difference between breath-hold and conventional imaging. To assess RV mass, we recommend RVIT view; the TIR sequence quickly produced images of better quality compared to gradient echo images but no significant difference between masses was found and repeatability of analysis was equally good with both methods.

MR gradient echo volumetric analysis of human cardiac casts: focus on the right ventricle.

PURPOSE: Our goal was to assess the utility of different imaging directions in volumetric studies of the heart with MRI, in particular to identify the optimal imaging plane for studies of the right ventricle. METHOD: We examined 12 sets of human four-chamber cadaveric cardiac casts. Gradient echo MRI was performed in four imaging planes: (a) perpendicular to the right ventricular inflow tract; (b) perpendicular to the right ventricular outflow tract; (c) in the left ventricular short axis view; and (d) in the axial view. The volumes of the right ventricle and other cardiac cavities were determined with the method of discs. The true cast volumes were measured with the water displacement technique. The agreement between true and measured volumes and the repeatability of image analysis were determined using the Bland-Altman method. RESULTS: There were no statistically significant differences between the measured and true right ventricular volumes irrespective of the imaging plane. The axial plane gave the smallest mean absolute difference from the true right ventricular volume (3.2 +/-2.2 ml) and also the best repeatability of volume analysis (0.2+/-1.6 ml). However, the other imaging planes performed nearly as well, and the differences across the planes were not statistically significant (p > 0.05). Also, in studies of the left ventricle and left and right atrium, the axial view appeared to give the best results, but differences across the imaging planes remained small. CONCLUSION: The present studies of human cardiac casts suggest that gradient echo MRI is well applicable to right ventricular volume measurements. Imaging the right ventricle in axial planes covering the entire heart gives good agreement with true right ventricular volumes and excellent analysis reproducibility. However, other imaging directions perform nearly as well, and thus selection of the imaging plane may not be of major importance to the accuracy of cardiac volume measurements with MR.

Bulimia and tooth erosion.

Eating disorders are often associated with regurgitation of gastric contents into the mouth and dental erosion. In this study the dental status was evaluated in bulimic patients. Thirty-five bulimics, diagnosed in the Outpatient Departments of Psychiatry and Adolescent Psychiatry of the University Central Hospital in Helsinki, and 105 controls matched for age, sex, and educational level were examined clinically, and the factors associated with dental erosion and caries were evaluated in an interview. Severe dental erosion and dental caries were significantly commoner among bulimics than controls. Bulimics commonly had a low salivary flow rate, but other apparent risk factors of dental erosion did not differ from those of controls. A feeling of dry mouth was commoner among bulimics than controls, and bulimics had an increased tooth sensitivity to cold and touch. More should be done to protect teeth from dental erosion among bulimics, because loss of tooth tissue remains even if the eating disorder disappears.

Bilateral diaphragmatic weakness: a late complication of radiotherapy.

Brachial plexus neuropathy is an unfortunate complication that sometimes follows radiotherapy to the axillary and supraclavicular regions. A patient is described who, 30 years after radiotherapy for Hodgkin's disease and more than 10 years after the development of radiation-induced bilateral brachial plexus neuropathy, presented with bilateral diaphragmatic weakness secondary to bilateral phrenic nerve weakness. Previous radiotherapy was the most probable cause of the condition.

Assessment of right and left atrial function in patients with transplanted hearts with the use of magnetic resonance imaging.

BACKGROUND: The purpose of this study was to determine the volumes and cyclic volume changes of the cardiac atria after heart transplantation in physically healthy recipients. METHODS: Ten heart transplant recipients (New York Heart Association grade I) entered the protocol. All operations had been made with classic biatrial anastomoses. Eight healthy volunteers were studied as controls. To measure the volumes of both atria and left ventricular cavity, we used a gradient-echo cine sequence. The 10 mm slices covered both atria over the total cardiac cycle. Images were planimetered, and simultaneous volumes were totalled to give the cavity volume at each time phase. RESULTS: The heart rate of the heart transplant recipients was faster than in controls, which resulted in higher cardiac output. The atrial minimum volumes were significantly larger, and fractional emptying was smaller in transplanted hearts when compared with controls. Reservoir and stroke volumes were smaller and conduit volumes were larger in transplanted hearts than in controls. The atrial filling and emptying rates were lower in heart transplant recipients than in controls. CONCLUSIONS: The classic surgical technique used in heart transplantation results in large atria with decreased volume changes and filling rates even in physically healthy transplant recipients. Magnetic resonance imaging is a reliable tool in assessment of atrial volumes and cyclic function after heart transplantation.

Right and left atrial phasic volumetric function in mildly symptomatic dilated and hypertrophic cardiomyopathy: cine MR imaging assessment.

PURPOSE: To characterize biatrial phasic volumetric function in dilated and hypertrophic cardiomyopathy with cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eight patients with dilated cardiomyopathy (mean age, 47 years), eight with hypertrophic cardiomyopathy (mean age, 39 years), and eight healthy subjects (mean age, 41 years) underwent cardiac-gated long-axis cine MR imaging of both atria. RESULTS: Left atrial minimum volume averaged 94 mL +/- 37 (standard deviation) in dilated cardiomyopathy, 86 mL +/- 40 in hypertrophic cardiomyopathy, and 51 mL +/- 14 in control subjects (P = .04). Left atrial ejection fraction averaged 16% +/- 6 in dilated cardiomyopathy, 19% +/- 12 in hypertrophic cardiomyopathy, and 28% +/- 7 in control subjects (P = .03). Right atrial minimum volume and ejection fraction were not altered in either form of cardiomyopathy. The normalized filling and emptying rates of either atrium were decreased in both forms of cardiomyopathy. CONCLUSION: In mildly symptomatic dilated and hypertrophic cardiomyopathy, and left atrium is enlarged and its relative cyclic volume changes are reduced. The right atrium is of normal size, but its reservoir function is compromised particularly in dilated cardiomyopathy. Three-dimensional volume measurements with cine MR imaging enable the exposure of altered atrial volumetric function.

A simplified method for the determination of left atrial size and function using cine magnetic resonance imaging.

This work aimed at developing a rapid and clinically applicable method for the assessment of left atrial size and function using magnetic resonance imaging (MRI). We studied 17 healthy subjects and 26 cardiac patients. Left atrial cine MRI with 50 ms phases was made in 6-12 contiguous long-axis sections encompassing the entire atrial cavity. A volume-time curve was reconstructed to measure the minimum and maximum volumes as well as the fractional volume change, reservoir function, ejection fraction, and mean filling and emptying rates of the left atrium. The image section with the largest left atrial area was then selected and a comparable area-time curve was reconstructed. The atrial phasic areas and functional indices were determined analogously to the volume-based assessment. The contours of atrial area-time and volume-time curves agreed closely in individual subjects. All area-based left atrial measurements distinguished cardiac patients as a group from healthy persons. The combined specificity of the area-based analyses was 92% and the sensitivity, 65%, in identifying abnormal results in individual patients. The accuracy of the area-based data was best for the atrial minimum size, fractional change, reservoir function, and mean filling rate. The estimated time savings with the simplified method were 5 to 6 h per patient. Left atrial size and function can be studied by reconstructing a phasic atrial area-time curve with cine MRI. Atrial enlargement and abnormalities of filling and reservoir function can be reliably identified, but if data on conduit or stroke function are crucial the three-dimensional MRI technique is still recommended.

Skewness of instantaneous mitral transannular flow-velocity profiles in normal humans.

The spatial distribution of instantaneous diastolic flow velocities across the mitral annulus was studied with cardiac gated cine magnetic resonance imaging in 10 healthy persons aged 26-46 yr. Velocity encoding used two interleaved gradient echo pulse sequences with velocity sensitivity in the direction of flow perpendicular to the annular imaging plane. Velocity maps were reconstructed at 30- to 43-ms intervals throughout diastole. Velocity-time curves and mean flow rates were determined in five regions of the mitral annulus using a 0.6-cm2 measurement area. The spatial velocity minimum was consistently in the anterolateral commissural area, whereas the maximum was in the anterior annulus in early diastole shifting posteromedially in late diastole. The mean flow rate (+/- SD) averaged 18.4 +/- 8.1 ml.s-1.cm-2 of annular area centrally, 18.3 +/- 7.2 ml.s-1.cm-2 anteriorly, 16.9 +/- 7.4 ml.s-1.cm-2 posteriorly, 13.0 +/- 7.7 ml.s-1.cm-2 in the anterolateral commissural area, and 23.0 +/- 7.3 ml.s-1.cm-2 in the posteromedial commissural area (P < 0.001). We conclude that mitral transannular flow shows marked spatial inhomogeneity in normal humans. The skewness of flow profiles compromises the use of local velocity measurements as indexes of left ventricular filling.

Right atrial MR imaging studies of cadaveric atrial casts and comparison with right and left atrial volumes and function in healthy subjects.

PURPOSE: To assess magnetic resonance (MR) imaging of the right atrium by measuring volumes of right atrial casts and determining right atrial volume cycles in healthy subjects. MATERIALS AND METHODS: Fourteen human cadaveric atrial casts were imaged and right atrial volumes of eight subjects were measured with cardiac-gated cine MR. Volumes were calculated and right and left atrial volumes were compared. RESULTS: Measured volumes of right atrial casts correlated well (r = .99, P < .001) with true volumes with a small underestimation noted (-7.2 mL +/- 2.3 [standard deviation], P < .001). The maximum in vivo right atrial volume averaged 77 mL/m2 +/- 11 of body area. The right atrial reservoir and conduit functions accounted for, on average, 58% and 19%, respectively, of the ventricular stroke volume; the remaining 23% came from atrial contraction. Right-to-left peak volume ratio averaged 1.41 +/- 0.15 (P < .001), and all volume measurements except conduit volumes were statistically significantly larger in the right atrium than the left. CONCLUSIONS: MR imaging provides a reliable means to study right atrial volumes and phasic function.

Occupational syrup-tasting and dental health.

In the sugar industry the quality of a syrup is judged by taste. The aim of this study was to investigate whether tasting affected the taster's teeth. Seven technicians who had tasted syrups for at least 2 years and 21 age-matched controls working in the same factory were investigated. Dental, medical, and dietary histories were obtained, and salivary and intra-oral examinations were undertaken. The tasters had similar DMFS indices to but more decayed surfaces than the controls (3.4 versus 1.0; p < 0.05), especially on proximal surfaces (2.0 versus 0.7; p < 0.05). The tasters had also higher visible plaque index and gingival bleeding index than the controls (23% versus 11% and 23% versus 10%; p < 0.05). We conclude that frequent exposure to syrup may increase caries activity, despite the various preventive measures commonly adopted. It is concluded that those selected for tasting should be carefully examined for general health and oral status and that preventive dental measures be emphasized.

Location of dental erosion in a referred population.

The aim of the study reported here was to determine locations of dental erosion and whether or not it is possible to decide the cause of erosion from the location. One hundred and six patients with dental erosion, 54 men and 52 women, mean age of 33.6 years, were studied. Erosion was classified as one of three grades on buccal, lingual or occlusal/incisal surfaces. Dietary and gastric causes of erosion were identified by means of a questionnaire. Erosion was observed on all teeth, but was commonest on the upper incisors, canines and premolars, and severest on palatal surfaces. In both groups, in which erosion had gastric and dietary causes, there were cases of buccal, lingual and occlusal erosion, but the risk of lingual erosion was 1.9 times greater in the group in which erosion had a gastric cause than in the group in which erosion had a dietary cause. Our findings indicate, however, that the cause of dental erosion cannot reliably be identified by location of the lesion.

Risk factors in dental erosion.

Dental erosion and factors affecting the risk of its occurrence were investigated with a case-control approach. One hundred and six cases with erosion and 100 randomly selected controls from the same source population were involved in the study. All cases and controls were evaluated by the recording of structured medical and dietary histories and by examination of the teeth and saliva. Erosion was classified according to pre-determined criteria. The relative importance of associations between factors and erosion was analyzed by a logistic multivariable model. Adjusted odds ratios (AOR) were estimated. There was considerable risk of erosion when citrus fruits were eaten more than twice a day (AOR 37), soft drinks were drunk daily (AOR 4), apple vinegar was ingested weekly (AOR 10), or sport drinks were drunk weekly (AOR 4). The risk of erosion was also high in individuals who vomited (AOR 31) or exhibited gastric symptoms (AOR 10), and in those with a low unstimulated salivary flow rate (AOR 5).

Experimental sports drinks with minimal dental erosion effect.

The effects of new experimental sports drinks on dental enamel were studied in vitro using bovine tooth specimens. Profilometric analysis was used to measure the loss of tooth material after immersion of the specimens in the drinks. Thereafter the specimens' surface hardness was measured and scanning electron microphotographs were taken. In addition, 13 commercial sports drinks and experimental drinks containing either citric acid or malic acid were tested for their capacity to dissolve hydroxyapatite in vitro. The erosive effect increased markedly with decreasing pH. The citric acid containing drinks were more erosive than malic acid containing drinks. No erosion was observed with the malic acid containing drink (pH 5.90) but the drink of similar composition containing citric acid caused an erosion 1.3 +/- 1.1 microns deep and a commercial citric acid containing drink caused a lesion 12.3 +/- 4.5 microns deep after 120 min immersion. Softening of enamel was greater in specimens immersed in citric acid than in those immersed in malic acid containing drink. The in vitro hydroxyapatite dissolving effect of the commercial sports drink samples studied (all having a pH under 4.22) was markedly greater (0.48-4.38 mmol/l) than that of the malic acid containing experimental drink (pH 5.50, Ca++ concentration in the supernatant 0.19 mmol/l) and of the similar citric acid containing drink (0.35 mmol/l). The hydroxyapatite dissolving effect of both drinks started to be marked at a pH level of about 5.0 but increased thereafter exponentially with decreasing pH. At pH levels above 4.0 the hydroxyapatite dissolving effect of citric acid containing drinks was greater than that of malic acid containing drinks.

Dental erosion and upper gastrointestinal disorders.

The orodental status, particularly dental erosions, of 109 patients with upper gastrointestinal symptoms was examined. In 44 patients, the underlying pathosis was associated with increased acid output in the stomach (reflux esophagitis or duodenal ulcer), while in 48 patients who underwent cholecystectomy, the duodenogastric reflux was alkaline. In 17 patients with gastric ulcer, the gastric secretion was usually normal. The diagnoses were made with gastroscopy. Seven patients with dental erosion were found, and they all came from the group of 35 dental patients with reflux esophagitis or duodenal ulcer. No erosions were seen in the other diagnostic groups (F = 0.02). Thus, gastrointestinal disorders with increased output of gastric acid may be linked with dental erosions. The finding emphasizes the need for accurate diagnosis and appropriate treatment of patients with upper gastrointestinal symptoms in order to avoid irreversible lesions in the teeth.

Lead content of deciduous molar enamel in Finland, as measured by proton-induced X-ray emission.

The lead content of deciduous molar enamel was measured with an accurate physical technique based on proton-induced X-ray emission. The absolute values were calibrated according to the animal bone standard of the International Atomic Energy Agency. The results obtained from five different communities indicated little difference between communities in the lead content of the deciduous molar enamel of children born in 1960-1975. The overall mean for all samples analyzed was 3.2 (SD 1.6) micrograms/g (N = 120); the highest individual value measured was 10.0 micrograms/g. Judging from the lead content of the teeth, the general population in Finland does not yet seem to be exposed to detectably higher amounts of artificially occurring environmental lead, neither in urban nor in rural areas. It would seem that naturally occurring environmental lead still plays a decisive role in the integrated long-term exposure in Finland.